For VLC player, go to Settings>Preferences>Video>>Output Modules. Tick the Advanced Options and set Video output module to X11 video output. Save your settings and restart your application.
For mplayer, go to preferences>video>available drivers. select X11 (OpenGL). Save your settings and restart your application.
For Kaffeine, go to settings>xine Engine Prameters>video. Select opengl. save your settings. restart Kaffeine.
if after changing these settings, you still unable to play your videos, you need to reset your screen resolution. When I change the resolution to 1280 x 1024, I cant play my videos ( with openGl, slow display motion

Please note that I mentioned the settings that worked for me.
os:debian 4.6.18*
desktop:kde